1. Field of the Invention
The invention is related to the field of electromagnetic fluid pumps and in particular to improvements of the reciprocating piston electromagnetic fluid pumps of the type disclosed by Dickey et al in U.S. Pat. No. 2,764,098.
2. Description of the Prior Art
The reciprocating piston fluid pump disclosed by Dickey et al in U.S. Pat. No. 2,764,098 has found wide acceptance in the commercial market and is extensively used for many different types of applications. The electromagnetic fluid pump has gone through many iterations, but its basic physical structure has remained relatively unchanged. The evolution of this electromagnetic fluid pump is evident from the following U.S. patents which disclose some of the improvements and variations of this pump over the years. U.S. Pat. No. 2,765,747 issued to Aumich; U.S. Pat. No. 2,833,221 issued to Dickey et al; U.S. Pat. No. 3,381,616 issued to Wertheimer et al; U.S. Pat. Nos. 4,080,552, 4,122,378, and 4,343,597 issued to Brown; U.S. Pat. No. 4,086,518 issued to Wilkinson; and U.S. Pat. No. 4,413,950 issued to Wiernicki. This fluid pump has three discrete internal chambers, an input chamber connected to an input port, an outlet chamber connected to an outlet port, and an intermediate chamber housing a solenoid coil and associated electronics. The intermediate chamber is normally back filled with an inert gas to prevent oxidation of electrical contacts and deterioration of the solenoid coil and the associated electrical components. The sealing between the separate chambers and the sealing of the housing itself in all of these different embodiments is accomplished with tin-plated solder joints. It was felt that these solder joints were necessary for the structural integrity of the pump and were less subject to leakage and other fatigue type failures over the life of the pump. Although the solder joints proved to be very effective in maintaining the seals between the three internal chambers of the pump, it was found that the flux used in making these solder joints was having adverse effects on the electronics and also the solder seals made it uneconomical to disassemble the pump for repair or salvage of its parts. The invention is a redesigned pump structure which eliminates selected solder joints and permits the pump to be disassembled for repair or salvage.